Invasive Animals

The introduction of exotic predators posed a substantial challenge to the native biodiversity. Unable to adapt quickly to predation and new diseases, many birds and other forms of life died off rather quickly. Today, both invasive predators (feral cats, rats) and other non-native mammals who alter habitat (cows, goats) continue to pose the most serious threat to biodiversity.

Feral Cats - Feral cats have invaded every major Hawaiian Island and pose substantial risks to endangered birds. These cats, which were probably domesticated at first, are now wild and untamed. They live in the wild where they have turned into top predators that feed on birds who nest on the ground. Cats can kill many birds and their eggs.

Mongooses - These small, fast creatures were introduced into Hawaii to reduce the booming rat population that was wreaking havoc on sugar cane plantations in the 19th century. Unfortunately, rather than solve the problem, mongooses developed an appetite for ground nesting birds and eggs. Now these mammalian predators have no natural predators and are overflowing the islands.

Rats - Brought by both Polynesians and Europeans, rats prey both on native birds and endemic vegetation. Where mongooses largely are active during the day, rats do their work at night, supplying 24-hour long threats to native species.

Cows, Goats, Pigs - Large tracts of land are cleared out so cows and other mammals can graze. Such deforestation destroys habitat and fragments the landscape, making it difficult for species to travel. Many of these herbivores also freely roam the wild, destroying vegetation throughout the rainforests.

A feral cat peeks into a Hawaiian Petrel burrow for eggs, Darcy Hu

Brought to Hawaii to control the rat population, Indian mongooses now prey on native birds, U.S. Forest Service

Feral pigs cause extensive damage to Hawaiian forests, U.S. Geological Survey